A biopsychologist is interested in how quickly rats learn a complicated maze.He puts 5 rats,labeled A,B,C,D,and E,in a box.He wants to run two of the rats through a maze,one rat at a time.How many subsets of 2 rats could he choose to run through the maze if order does NOT matter?
A)10
B)15
C)20
D)40

Question

Quizplus · Accepted Answer

The number of ways to choose 2 rats from 5 when order does not matter is given by the combination formula C(n, k) = n! / (k!(n-k)!), where n is the total number of items to choose from, and k is the number of items to choose. Here, C(5, 2) = 5! / (2!(5-2)!) = 10.

A Biopsychologist Is Interested in How Quickly Rats Learn a Complicated